Chemically activated phosphate slime as adsorbent for heavy metals removal from polluted water

Phosphate slime was activated by chemical activators (0.5 M HNO₃, 1 M HNO₃, 2MHNO₃, 0.5MHNO₃: 0.5M NaOH, 1MHNO₃: 1M NaOH, and 2MHNO₃: 2M NaOH) to use as a cost-effective adsorbent for removal of heavy metals (Pb, Ni, Cd, Zn and Cu) from solution. The influence of pH, adsorbent dosage, contact time, initial metal concentration, and temperature on metals adsorption were investigated. Results revealed that slime phosphate activated by 2MHNO₃ was an effective adsorbent for the removal of all metals from aqueous solution. Metal removal was affected by pH, adsorption dosage, initial metal concentration and solution temperature, while it shows less significant for effect of contact time. Metal adsorption was in a good correspondence with the Langmuir isotherm. The order for the maximum adsorption using the adsorbent was Zn (43.47 mg/g) > Cu (38.46 mg/g) > Ni (34.47 mg/g) > Pb (33.3 mg/g) > Cd (26.31 mg/g).